From 4038f52cdf4c1e9f16e391a5b7dff2cec14a10d0 Mon Sep 17 00:00:00 2001
From: Uwe Rathmann <Uwe.Rathmann@tigertal.de>
Date: Tue, 10 Jan 2023 12:17:56 +0100
Subject: [PATCH] inverted gradient vectors for horizontal/vertical gradients
 supported

---
 src/common/QskGradientStop.cpp | 11 +++++++++++
 src/common/QskGradientStop.h   |  2 ++
 src/nodes/QskBoxRenderer.cpp   | 32 ++++++++++++++++++++++++++++----
 3 files changed, 41 insertions(+), 4 deletions(-)

diff --git a/src/common/QskGradientStop.cpp b/src/common/QskGradientStop.cpp
index 9874c683..4455d5c8 100644
--- a/src/common/QskGradientStop.cpp
+++ b/src/common/QskGradientStop.cpp
@@ -312,6 +312,17 @@ QskGradientStops qskExtractedGradientStops(
     return extracted;
 }
 
+QskGradientStops qskRevertedGradientStops( const QskGradientStops& stops )
+{
+    QVector< QskGradientStop > s;
+    s.reserve( stops.count() );
+
+    for ( auto it = stops.crbegin(); it != stops.crend(); ++it )
+        s += QskGradientStop( 1.0 - it->position(), it->color() );
+
+    return s;
+}
+
 QVector< QskGradientStop > qskBuildGradientStops( const QGradientStops& qtStops )
 {
     QVector< QskGradientStop > stops;
diff --git a/src/common/QskGradientStop.h b/src/common/QskGradientStop.h
index 22dbc397..b58a0d77 100644
--- a/src/common/QskGradientStop.h
+++ b/src/common/QskGradientStop.h
@@ -145,6 +145,8 @@ QSK_EXPORT QskGradientStops qskBuildGradientStops(
 QSK_EXPORT QskGradientStops qskBuildGradientStops(
     const QVector< QColor >&, bool discrete = false );
 
+QSK_EXPORT QskGradientStops qskRevertedGradientStops( const QskGradientStops& );
+
 QSK_EXPORT QskGradientStops qskBuildGradientStops( const QVector< QGradientStop >& );
 QSK_EXPORT QVector< QGradientStop > qskToQGradientStops( const QVector< QskGradientStop >& );
 
diff --git a/src/nodes/QskBoxRenderer.cpp b/src/nodes/QskBoxRenderer.cpp
index 4d02c61c..23670380 100644
--- a/src/nodes/QskBoxRenderer.cpp
+++ b/src/nodes/QskBoxRenderer.cpp
@@ -11,6 +11,30 @@
 #include "QskGradient.h"
 #include "QskGradientDirection.h"
 
+static inline QskGradient qskNormalizedGradient( const QskGradient gradient )
+{
+    const auto dir = gradient.linearDirection();
+    if ( !dir.isTilted() )
+    {
+        /*
+            Dealing with inverted gradient vectors makes the code even
+            more unreadable. So we simply invert stops/vector instead.
+         */
+        if ( ( dir.x1() > dir.x2() ) || ( dir.y1() > dir.y2() ) )
+        {
+            QskGradient g = gradient;
+            g.setLinearDirection( dir.x2(), dir.y2(), dir.x1(), dir.y1() );
+
+            if ( !g.isMonochrome() )
+                g.setStops( qskRevertedGradientStops( gradient.stops() ) );
+
+            return g;
+        }
+    }
+
+    return gradient;
+}
+
 void QskBoxRenderer::renderBorder(
     const QRectF& rect, const QskBoxShapeMetrics& shape,
     const QskBoxBorderMetrics& border, QSGGeometry& geometry )
@@ -36,15 +60,17 @@ void QskBoxRenderer::renderBox( const QRectF& rect,
     const QskBoxBorderColors& borderColors, const QskGradient& gradient,
     QSGGeometry& geometry )
 {
+    const auto gradientN = qskNormalizedGradient( gradient );
+
     if ( shape.isRectangle() )
     {
         QskRectRenderer::renderRect(
-            rect, border, borderColors, gradient, geometry );
+            rect, border, borderColors, gradientN, geometry );
     }
     else
     {
         QskRoundedRectRenderer::renderRectellipse(
-            rect, shape, border, borderColors, gradient, geometry );
+            rect, shape, border, borderColors, gradientN, geometry );
     }
 }
 
@@ -70,8 +96,6 @@ bool QskBoxRenderer::isGradientSupported(
         case QskGradient::Linear:
         {
             const auto dir = gradient.linearDirection();
-            if ( dir.x1() > dir.x2() || dir.y1() > dir.y2() )
-                return false;
 
             if ( shape.isRectangle() )
             {